The position of a mobile device can be estimated based on wireless signals transmitted by wireless access points (APs) and received by the mobile device. If the mobile device knows the locations of the APs, the mobile device can estimate the position by using measurements of the wireless signals to calculate the distance or range between the mobile device and each AP. If the mobile device does not have the locations of the APs stored locally, the data can be requested from a server and downloaded.
Depending on the situation, there can be many APs in an area. To help organize the data for the APs and reduce the number of requests, the APs can be grouped into “tiles” based on their geographical location. Thus, a tile represents a geographical area in which a plurality of APs is located. The mobile device requests and downloads data for tiles from the server rather than individually for each AP. However, the number of APs in a tile and the amount of data for a tile can be very large, especially in areas with high population density. This can result in long download times, high power consumption when downloading, and the downloaded data taking up a large portion of the mobile device's memory.